diff --git a/pkg/rudus.js b/pkg/rudus.js
index b37dd12..b048e8d 100644
--- a/pkg/rudus.js
+++ b/pkg/rudus.js
@@ -403,7 +403,7 @@ function __wbg_get_imports() {
         _assertBoolean(ret);
         return ret;
     };
-    imports.wbg.__wbindgen_closure_wrapper8087 = function() { return logError(function (arg0, arg1, arg2) {
+    imports.wbg.__wbindgen_closure_wrapper8088 = function() { return logError(function (arg0, arg1, arg2) {
         const ret = makeMutClosure(arg0, arg1, 354, __wbg_adapter_20);
         return ret;
     }, arguments) };
diff --git a/pkg/rudus_bg.wasm b/pkg/rudus_bg.wasm
index fb31310..ec8f808 100644
Binary files a/pkg/rudus_bg.wasm and b/pkg/rudus_bg.wasm differ
diff --git a/src/validator.rs b/src/validator.rs
index fdd73cf..3c6527f 100644
--- a/src/validator.rs
+++ b/src/validator.rs
@@ -1,12 +1,11 @@
 // TODO:
-// * [ ] ensure `or` and `and` never get passed by reference
-// * [ ] ensure no placeholder in `or` and `and` args
 // * [ ] ensure loops have fixed arity (no splats)
 // * [ ] ensure fn pattern splats are always highest (and same) arity
 
 use crate::ast::{Ast, StringPart};
 use crate::spans::{Span, Spanned};
 use crate::value::{Key, Value};
+use std::cmp::max;
 use std::collections::{HashMap, HashSet};
 
 #[derive(Clone, Debug, PartialEq)]
@@ -230,6 +229,9 @@ impl<'a> Validator<'a> {
                 if members.is_empty() {
                     return;
                 }
+                if members.len() > 7 {
+                    self.err("tuples may not have more than 7 members".to_string());
+                }
                 let tailpos = self.status.tail_position;
                 self.status.tail_position = false;
                 for member in members {
@@ -242,6 +244,9 @@ impl<'a> Validator<'a> {
                 if args.is_empty() {
                     return;
                 }
+                if args.len() > 7 {
+                    self.err("tuples may not have more than 7 members".to_string());
+                }
                 let tailpos = self.status.tail_position;
                 self.status.tail_position = false;
                 for arg in args {
@@ -423,6 +428,43 @@ impl<'a> Validator<'a> {
                     self.validate();
                 }
 
+                let mut max_arity = 0;
+                let mut has_splat = false;
+                for arity in arities.iter() {
+                    match arity {
+                        Arity::Fixed(n) => {
+                            max_arity = max(*n, max_arity);
+                        }
+                        Arity::Splat(n) => {
+                            max_arity = max(*n, max_arity);
+                            has_splat = true;
+                        }
+                    }
+                }
+
+                for arity in arities.iter() {
+                    match arity {
+                        Arity::Fixed(n) => {
+                            if *n == max_arity && has_splat {
+                                self.err(
+                                    "splats must be the longest arity in function clauses"
+                                        .to_string(),
+                                );
+                                break;
+                            }
+                        }
+                        Arity::Splat(n) => {
+                            if *n > max_arity {
+                                self.err(
+                                    "splats must be the longest arity in function clauses"
+                                        .to_string(),
+                                );
+                                break;
+                            }
+                        }
+                    }
+                }
+
                 // collect info about what the function closes over
                 let mut closed_over = HashSet::new();
                 for binding in self.status.used_bindings.iter().skip(from) {
@@ -497,7 +539,7 @@ impl<'a> Validator<'a> {
                         }
                         Arity::Splat(clause_arity) => {
                             if clause_arity > loop_arity {
-                                self.err(format!("mismathced arity: expected {loop_arity} arguments in `loop` clause; this clause takes {clause_arity} or more"))
+                                self.err("loop clauses may not have splats".to_string())
                             }
                         }
                     };
@@ -516,6 +558,9 @@ impl<'a> Validator<'a> {
                 if !self.status.tail_position {
                     self.err("you may only use `recur` in tail position".to_string());
                 }
+                if args.len() > 7 {
+                    self.err("tuples may only have 7 members".to_string());
+                }
 
                 let num_args = args.len() as u8;
                 let loop_arity = self.status.loop_arity;
@@ -583,7 +628,25 @@ impl<'a> Validator<'a> {
                     }
                 }
             }
-            TuplePattern(terms) | ListPattern(terms) | DictPattern(terms) => {
+            TuplePattern(terms) => {
+                if terms.is_empty() {
+                    return;
+                }
+
+                if terms.len() > 7 {
+                    self.err("tuples may only have 7 arguments".to_string())
+                }
+
+                for term in terms.iter().take(terms.len() - 1) {
+                    self.visit(term);
+                }
+
+                self.status.last_term = true;
+                let last = terms.last().unwrap();
+                self.visit(last);
+                self.status.last_term = false;
+            }
+            ListPattern(terms) | DictPattern(terms) => {
                 if terms.is_empty() {
                     return;
                 }